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be brain dead

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be brain dead

1. Literally, to lack brain activity, as after a brain injury. After the car accident, Kendra was brain dead. Despite the surgeon's best efforts, the patient was brain dead.

2. slang To be so mentally exhausted or lacking focus that one does something poorly and/or makes easily avoidable mistakes. Did I just say that two plus two equals five? Wow, I'm really brain dead today.

See also: brain, dead

be brain dead

  (humorous)

if someone is brain dead, their mind is not working effectively, usually because they are very tired or very bored By the time I leave work I'm completely brain dead.

See also: brain, dead